Artificial horizon.



H. ANSCHUTZ-KABA*PFI-2I ARTIFICIAL'HHIZON.

APPLICATION FILED FEB27|`|914| Patented J une 1, 1915.

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H. ANSCIIUTZ-KAVEIVIPFE. ARTIFICIAL HORIZON.

APPLICATION FILED FEB. 27- .1914- Patented June 1, 1915.

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Specification of Letters Patent.

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Application filed February 27, 1914. Serial No. 821,353.

T all whom t may concern:

Be 1t known that I, HERMANN ANsGHTzl KAEMPFE, asubject of the Emperor of Gerter of many, residing at Heikendorferweg 9, Neumhlen, near Kiel, Germany, ha ve invented certain new and useful Improvements in Artificial Horizons, of which the following is a. specification.

In order to determine in navigation the position of a ship, it is usual to measure the angle of elevation of heavenly bodies from the horizon. If the observation of the natura-l horizon is impossible, the so-called artificial horizon can be used. It consists generally of a reflecting surface of a liquid,

but numerous experiments have already been made with gyroscopic apparatus in which the axis of rotation is vertical, and the cengravity is in, or above, or below the line of support. A liquid mirror has the tendency to assume a position normal to the resultant of gravity and the acceleration pressure at the moment, so that it can be used only when the ship is perfectly still.

Gyroscopic apparatus are less affected by the movements of ships, as a single acceleration pressure produces only a very slight oscillation, and acceleration pressures of opposite directions neutralize each other during a complete period of .precession of the gyroscope. In order to insure the necessary accuracy, a long period of precession mustl be adopted, for which purpose the center of gravity must be brought ars close to the point of support, as possible. In order to elii inate errors due to the precession, each observation must be repeated after a half period of precession. Eor that purpose, it is however desirable to have the shortest possible time of precession, which would necessitate the largest possible distance between the center` of gravity and point of support. Apparatus hitherto known have the disadvantage that they comply only with one of these two contradictory conditions.

To avoid the difficulty in question, vthe artificial horizon is given, according to this invention, different ldegrees of accuracy, in two planes at a'right angle to each other and arranged sothat the plane of greatest accuracy can be turned in the direction of the heavenly body to be observed. In practical construction, this is attained by placing the two Cardan axes at different levels above the center of gravity, and by rotatably v into the direction v laws, about the cured at a suitable apparatus in such a an axls nearest to the arranging the whole manner that the Card center of gravity,

of observation. The acceleratlon pressures acting with reference 'to the said axis, have therefore a short lef,

verage, and consequently produce only a small precession movement. This movement takes place, in accordance with gyroscopic Cardan axis which is normal to the direction of observation, that is to say, in the direction in which great accuracy is required. On the other hand, the moment of the forces acting at the center of gravity, about the axis normal to the direction of observation, is comparatively large so that the oscillations subside quickly, as desired for a quick servations. i

The artificial horizon according to this invention is further provided with a device can always be broughtsuccession of obby means of which the center 'of gravity o f the movable apparatus can be shifted relatively to the gyrosopic axis. Owing to this movement of the center of gyroscope is forced to effect a precession the magnitude and direction of which can be adjusted in such a manner that the gyroscopic axis' which would have retained, in itself, its direction in space, participates in the movement of the earth and remains always normal to the surface of the earth. A similar device is described in the U. S. patent specification No. 877034.

The drawings show diagrammatically a construction according to this invention, Figures 1 and 2 through the apparatus, at an angle 90 to each other. Fig. 3 is a plan, Fig. 4 detail view. f

1 indicates a leg or standwhich is sepoint of the ship Aor to a portable frame. In the said stand is rotatably mounted, by means of a cylindrical the rotatable casing 3 relativelyrto the fixed stand 1 can be read at this polnt. In the gravity, the

casing 3 is rotatably-supported about the axis 6 -6, 6, a ring 7 which in' its turn carries in cups and knife edges 8, an inclosedbox 9 which can swing about the axis 8 8.

The suspension of the box 9 within the casing 43 is similar, as shown'in Fig. 3,\to l by means of cups and knife edges an ordinary Cardan suspension, but diilers from the latter and this is an essential feature of the present invention by the fact that the axis of rotation6-6 does not in- Ltersect the axis of rotation 8 8. As will be seen in comparing Figs. 1 and 2, the two axes are, on the contrary, in diiferent planes, so that the. center of gravity of the box 9 and of the pa'rts secured to the same, is only a little below the axis 8 8, but considerably farther. below the axis 6 6 (for instance, two to ten times as far, according to the kind of ship and to the accuracy required). When motor is covered by the box and is there-fore not visible in the drawing.The box 9 is further provided nearits upper end with a mirror' 14: which is mounted exactly at a right angle; or. normally to the axis of the gyroscope. Moreover, on the box 9 is rotatably mounted a ring 15 which forms asupport for the regulating weight 16 by means of which the center of gravity of the system is moved out of the gyroscopic axis and the latter is forced to execute a precession compensating the motion of therotation of the.

earth. The weight 16'is mounted by means of a screwthread4 on a'screw 17 secured to therotatable ring -15 an'd can be rotated thereon. Its position and its distance from the axis of the gyroscope 13 can be read on a scale 20. To the box 9 is further secured an annular vessel 21 shown in Figs. 1' and 2 partly in section. This vessel is partly filled with 4a liquid such as mercury, oil or the like, and contains further a number of partitions -22 provided at the bottom with small passage openingsof adjustable size.

The result of this arrangement is that the precession movements of the gyroscope l about the vertical line are strongly damped if there is a considerable difference of hase between the precession movements o the liquid within the tube 21. According'to the law of energy, a certain quantitT of work or energy must be taken from the u roscope 1n order 'to damp its preces'sion.

- rangement described the amount of energy required is consumed by the friction forces during the passage of the liquid through the narrow openings in the partitions 22. It

mustv be pointed out that damping of oscillations of gyroscopic compasses about the 'horizontal axis, ,based on the same principles, is already well known, for instance from the U. S. patent-application Ser.` No. (531?!99'4 p regulating weight and damping vessel,

Awhich parts -will be hereinafter referred to as the movable system, can be observed through a glass-plate 12 of the casing 3. 'lhe glass-plate 12 can however be removed during the said observation. Finally, the casing 3 is provided at the ends of a diameter with a sighting device of well known kind, consisting of a pin 18 and of a slotted plate 10.

rlhe working of the device described is as .follows: Let it be first assumed that the center of gravity of the movable system is balanced so. that tl1e-`fnirror is horizontal when the gyroscope is not rotating, and that theregulating weight is adjusted for the latitude of 90. Let the gyroscope be then operated andl its axis come to rest, after exeouting a few oscillations of quickly decreasing amplitude, into the vertical line ofthe place where the apparatus is mounted.`

Owing to daily rotation of the earth, the said vertical line is fixed only with reference to the earth, While it always experiences a greater or less angular rotation in the world space. This rotation of the vertical line is greatest at the Equator, and decreases in higher latitudes, and inally becomes zero at the pole. If the axis of the gyroscope is to make `no movement relatively to the surface of the earth, it must execute a precession-in.l

space, the amount and direction of which must be equal to those of the rotation of the vertical line of the place where theapparatus is situated. To cause `such a preces- 7toward the east. The weight must therefore be arranged on the north or south according to the direction of rotation of the gyroscope. In order that it may be arranged at any moment in this point of the compass, it if rotatably mounted on the box 9 by means oi the ring 15. If the apparatus is brought to different latitudes, ,the magnitude of the turning momentum required alters. To that end, the weight can be shifted by means of the screw 17. In order to enable the weight to be conveniently adjusted, to the ring *15, next to thescrew 17, 1s secured the scale 20, preferably having indications of latitude.

The casing 3 being rotatablev in the stand 1,. the'whole apparatus to be adjusted, before the observations, with the assistance of the sighting device'18 and -19 in such a manner that the Cardan axis 8 8 coincides as exactly as possible with the direction of the heavenly body to be observed. As the center 0f gravity af the movable system, at which the acceleration pressure acts, is situated close under the axis in question, the disturb-v ing iniiuence of the said lacceleration pressures is in that way kept as low as possible.

ny desired acceleration pressure can be decomposed into three components at a right angle to eachother; the vertical component does not cause any'precessional movement,

` as long as the center of gravity of themovo accordance with gyroscopic laws,

movable system is able system is exactly in the vertical axis of,

the system. One horizontal component, in the direction of the axis" 8 8, produces, in a canting of the mirror about the axis 8 8, and the third component, inthe direction of the axis 6 6, a canting about the said axis. As already stated, the center of `gravity of the only very little below the axis 8 8. The component of a pressure, which acts in the directionof the axis 6 6, and, if the gyroscope did not rotate, would turn it about 8 8 acts therefore on the gyroscope only with a correspondingly small le verage. The canting of the rotating gyroscope about the axis 6 6 thus produced, will therefore also remain Ivery small and moreover will be so slow would be practically unaffected by pressures periodically altering their direction, such as for instance pitching. The matter is different with that component of any pressures, which acts in the direction of the axis 8 8 on the gyroscope. It engages with a larger leverage with the duces a greater oscillation ofthe same about the axis 8 8. The sta-rito be observed being however situated, as already stated, in the vdirection of the axis 8 8, no essential error of measurement' will be made, since only the cosine of the angle of error appears in' the equation, provided that the rotation of the mirror about the axis 8 8 is not too great. In other words the mirror is given, by mounting the axes 6 6 and 8 8 at vdifferent levels, two different degrees of accuracy, namely a very great one in the direction of observation, and a smaller one inthe direction at a right angle to the same, where inaccuracies are not so important. Owing to the center of gravity of the movable system being placed low in one plane, the pe- I riod for the complete precession ofthe gyroscope will however be considerably reduced. In case of a rotating gyroscope it is equal to the geometrical mean of the time of oscillation that the gyroscope would have if the twoy Cardan axes were situated at the same level as 6 6, and of the time of oscillation if the two Cardan axes'were at the level of the axis 8 8. The arrangement described therefore produces a gyroscope v coming to that the gyroscopes movable system and prov facture give then so much `smaller'angles of.

error.A In the construction described, the center of gravity is much lower under the mife edges 6 6, than under the knife edges 8 8. The mirror o will therefore remain more accurately normal to the knife edges 6 6 in the horizontal plane. This is however the direction in which the elevation of the object above the horizon is to be measured. Further, time of oscillation compared to the 'well known constructions, will become more particularly noticeable owing to the above described damping device bringing the gyroscope to a standstill in the vertical line after a few oscillations. If the time for a com plete oscillation of the gyroscope is short, the time from the starting of the motorto the moment when the apparatus is ready for working, will be much shorter than in the case of slowly oscillating gyroscopes.

Other arrangements couldl be made in place of the construction described in order to give the movable system, in accordance with the inventive idea, different times of oscillation relatively to the two Cardan axes. Thus, for instance, the Cardan axes could be arranged in the same plane, and the center of gravity of the movable system comparatively far below their point of intersection. rlhe movable system'can then be combined with a freeliquid vsurface of suitable shape which would act exactly as if the center of gravity of the movable system were shifted higher relatively to a plane. Y

The knife edges 6 6 and 8 8 which, ac-

the advantage of a shorterof gravity is cording to the foregoing description, have to carry Vthe whole weight of the movable system, could also be relieved by a float a shape that the metacenter is considerably higher in the plane of the knife than in the plane of the knife Another kind of damping selected for da ping the oscillations of the gyrosco e. Thus forlinstance according to the' U. patent application Ser. N o. 7 68739, an auxiliary pendulum couldbe secured to the movable system, which pendulum, when the gyroscope oscillates away from the vertica would release external turning mox ments about one of the Cardan axes, which edges 8 8, edges 6 6.

could also be ist would counteract the oscillations 'of the means and situated materially above the movable system. said center of gravity. i

What I claim is: v ln Witness whereof I have hereunto A n artificial horizon comprising a movsigned my namethis sixteenth day of Feb- 15 5 able system including a gyroscope having a ruary 1914 in the presence of two subscribiormally verticalh axis, susipelsiti means ing Witnesses. t

or sai system t e axis o w ic is situated closely above the center of gravity of DE' HERMNN'NSCHTZ'KEMPPE' the movable system, and further suspension Witnesses: 10 means the axisof which is at right angles A. V. W. Cown,

to the axis of the first-mentioned suspension W. ROEDEN. 

